The basic goal of the proposed research is to increase and stabilize the supply of voluntarily donated blood through theoretical understanding of donor motivations and the development of interventions in the donor recruitment process. There are two emphases in this research which have received little previous attention: (1) the process by which first time donors become committed regular donors and (2) the impact of situational factors on donors' perceptions and evaluations of donation experiences. A set of complementary research projects are proposed, beginning with reanalysis of several data sets already in hand and continued followup of a longitudinal sample of first time donors already obtained. Both a naturalistic study of additional first time donor samples and experimental interventions in the donation process are proposed. Three theoretical models are used to generate predictions regarding important factors in the process of developing internal motivations to donate; empirically related personal cost factors (e.g., waiting time) and other theoretical constructs (e.g., personal norms) are also examined in relationship to donor retention. Variables investigated include (1) personal characteristics such as motives for giving, attitudes, and background, and (2) situational factors, particularly aspects of the first donation experience. Separate studies of situational factors influencing in yield of blood, from site-to-site and from season-to-season are proposed.